U.S. patent application number 11/690247 was filed with the patent office on 2007-10-04 for signal degrade detecting method, signal restoration detecting method, devices for those methods, and traffic transmission system.
This patent application is currently assigned to NEC CORPORATION. Invention is credited to Toshiro YAMAUCHI.
Application Number | 20070230364 11/690247 |
Document ID | / |
Family ID | 38558744 |
Filed Date | 2007-10-04 |
United States Patent
Application |
20070230364 |
Kind Code |
A1 |
YAMAUCHI; Toshiro |
October 4, 2007 |
SIGNAL DEGRADE DETECTING METHOD, SIGNAL RESTORATION DETECTING
METHOD, DEVICES FOR THOSE METHODS, AND TRAFFIC TRANSMISSION
SYSTEM
Abstract
A method of detecting a signal degrade of transmission data, a
method of detecting a restoration from a signal degrade, and a
signal restoration detecting device are provided. The method of
detecting a signal degrade includes measuring a discarded data rate
of traffic; and comparing said discarded data rate with a threshold
value to detect the signal degrade. The method of detecting
restoration from a signal degrade includes obtaining a value by
multiplying a threshold value, used to detect a signal degrade, by
a multiplier; and comparing a discarded data rate of a control
traffic after a signal degrade with said value to detect a
restoration from the signal degrade. The device includes measuring
means for measuring a discarded data rate of traffic; threshold
value output means for outputting a threshold value; and detecting
means for detecting a signal degrade by comparing said discarded
data rate with said threshold value.
Inventors: |
YAMAUCHI; Toshiro; (Tokyo,
JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W., SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
NEC CORPORATION
Toyko
JP
|
Family ID: |
38558744 |
Appl. No.: |
11/690247 |
Filed: |
March 23, 2007 |
Current U.S.
Class: |
370/252 |
Current CPC
Class: |
H04L 43/16 20130101;
H04J 3/14 20130101; H04L 43/0847 20130101; H04L 1/203 20130101;
H04L 1/0061 20130101 |
Class at
Publication: |
370/252 |
International
Class: |
H04J 1/16 20060101
H04J001/16 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2006 |
JP |
100621/2006 |
Claims
1. A method of detecting a signal degrade of transmission data,
said method comprising: measuring a discarded data rate of traffic;
and comparing said discarded data rate with a threshold value to
detect the signal degrade.
2. The method according to claim 1, wherein said discarded data
rate is a discarded byte rate calculated according to a Frame Check
Sequence error.
3. The method according to claim 1, wherein the discarded data rate
is a discarded bit rate.
4. The method according to claim 1, further comprising storing a
result of the detection in a medium.
5. A method of detecting a restoration from a signal degrade of
transmission data, said method comprising: obtaining a value by
multiplying a threshold value, which is used to detect a signal
degrade, by a multiplier; and comparing a discarded data rate of a
control traffic after a signal degrade with said value to detect a
restoration from the signal degrade.
6. The method according to claim 5, wherein said discarded data
rate is a discarded byte rate calculated according to a frame check
sequence error.
7. The method according to claim 5, wherein the discarded data rate
is a discarded bit rate.
8. The method according to claim 5, further comprising storing a
result of the detection in a medium.
9. A method of detecting a restoration from a signal degrade of
transmission data, said method comprising: measuring a discarded
data rate of control traffic; if a signal degrade is detected,
saving said discarded data rate as a threshold value; and comparing
a discarded data rate of the control traffic measured after the
signal degrade is detected with said threshold value to detect a
restoration from the signal degrade.
10. The method according to claim 9, wherein said discarded data
rate is a discarded byte rate calculated according to a Frame Check
Sequence error,
11. The method according to claim 9, wherein the discarded data
rate is a discarded bit rate.
12. The method according to claim 9, further comprising storing a
result of the detection in a medium.
13. A method of detecting a restoration from a signal degrade of
transmission data, said method comprising: measuring a data error
rate of traffic; if a signal degrade is detected, saving said data
error rate as a threshold value; and comparing a data error rate of
the traffic measured after the signal degrade is detected with said
threshold value to detect a restoration from the signal
degrade.
14. The method according to claim 13, wherein said data error rate
is a bit error rate.
15. The method according to claim 13, further comprising storing a
result of the determination in a medium.
16. A signal degrade detecting device, comprising: measuring means
for measuring a discarded data rate of traffic; threshold value
output means for outputting a threshold value; and detecting means
for detecting a signal degrade by comparing said discarded data
rate with said threshold value.
17. The signal degrade detecting device according to claim 16,
wherein said discarded data rate is a discarded byte rate
calculated according to a frame check sequence error.
18. A signal restoration detecting device, comprising: measuring
means for measuring a discarded data rate of control traffic; and
detecting means for detecting a restoration from the signal degrade
by comparing said discarded data rate of the control traffic with a
value resulting from multiplying a threshold value which is used to
detect a signal degrade by a multiplier.
19. The signal degrade detecting device according to claim 18,
wherein said discarded data rate is a discarded byte rate
calculated according to a frame check sequence error.
20. A signal restoration detecting device, comprising: measuring
means for measuring a discarded data rate of control traffic;
saving means for, if a signal degrade is detected, saving said
discarded data rate as a threshold value; and detecting means for
detecting a restoration from the signal degrade by comparing a
discarded data rate of the control traffic measured after the
signal degrade is detected with said threshold value.
21. The signal degrade detecting device according to claim 20,
wherein the discarded data rate is a discarded byte rate calculated
according to a frame check sequence error.
22. A signal restoration detecting device, comprising: measuring
means for measuring data error rate of traffic; saving means for,
if a signal degrade is detected, saving said data error rate as a
threshold value; and detecting means for detecting a restoration
from the signal degrade by comparing a data error rate of traffic
measured after the signal degrade is detected with said threshold
value.
23. The signal restoration detecting device according to claim 22,
wherein the data error rate is a bit error rate.
24. A signal degrade detecting device, comprising: measuring unit
which is configured to measure a discarded data rate of traffic;
threshold value output unit which is configured to output a
threshold value; and detecting unit which is configured to detect a
signal degrade by comparing said discarded data rate with said
threshold value.
25. A signal restoration detecting device, comprising: measuring
unit which is configured to measure a discarded data rate of
control traffic; and detecting unit which is configured to detect a
restoration from the signal degrade by comparing said discarded
data rate of the control traffic with a value resulting from
multiplying a threshold value which is used to detect a signal
degrade by a multiplier.
26. A signal restoration detecting device, comprising: measuring
unit which is configured to measure a discarded data rate of
control traffic; saving unit which is configured to, if a signal
degrade is detected, save said discarded data rate as a threshold
value; and detecting unit which is configured to detect a
restoration from the signal degrade by comparing a discarded data
rate of the control traffic measured after the signal degrade is
detected with said threshold value.
27. A signal restoration detecting device, comprising: measuring
unit which is configured to measure data error rate of traffic;
saving unit which is configured to, if a signal degrade is
detected, save said data error rate as a threshold value; and
detecting unit which is configured to detect a restoration from the
signal degrade by comparing a data error rate of traffic measured
after the signal degrade is detected with said threshold value.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from Japanese Patent
Application No. 2006-100621, filed on Mar. 31, 2006, in the
Japanese Patent Office, the disclosure of which is hereby
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Methods and apparatuses consistent with the present
invention relate to a signal degrade detecting method, a signal
restoration detecting method, devices for those methods, and a
traffic transmission system, which are suitable for precisely
discriminating the signal degrade of a transmission line.
[0004] 2. Description of the Related Art
[0005] A packet network has been constructed in a communication
system, and in recent years, demand for enhancing reliability in
such networks has been increasing. There has been proposed a
communication system in which the signal degrade of a traffic
triggers a protection in the packet network as in the related art
Synchronous Data Hierarchy (SDH) system. For example, in the
Resilient Packet Ring (RPR) that is governed by the IEEE 802.17
standard, the signal degrade of the transmission line is defined as
one of a number of protection triggers.
[0006] In the packet network described above, the packet
communication system such as the ethernet which has a high affinity
with the packet network has been frequently employed.
[0007] However, packet communication systems including the
above-described ethernet present some problems.
[0008] A problem with such packet systems is that the packet
communication system does not have a function of monitoring a bit
error rate as is present in the SDH system. Thus, the signal
degrade of the transmission line cannot be detected. Therefore, the
transmission line that experiences signal degrade cannot be changed
to the normal transmission line by the protection when a error
attributable to the signal degrade of the transmission line
occurs.
[0009] Another problem is that, in the packet communication system,
the discarded data rate of the actual traffic, that is, how much
traffic volume is not normally transmitted, cannot be measured even
if the bit error rate is measured, since the traffic volume to be
discarded depends on the length of the packets. Accordingly, even
when the bit error rate is being measured, the discarded data rate
of the traffic cannot be measured. In the packet communication
system including ethernet, the signal degrade of the transmission
line is detected by a Frame Check Sequence (FCS) error that
performs error detection of the packet. Thus, even if only a part
of a packet has an error, the entire packet is discarded. Thus,
there arises a problem in that a state in which a large amount of
traffic is discarded cannot be actually determined by merely
measuring the bit error rate. Specifically, in the case where a
large number of packets of the traffic are long length packets, and
in the case where a large number of packets of the traffic are
short length packets, even if the bit error rates are the same, the
traffic volume to be discarded in the former case becomes larger.
Also, there is the possibility that most of the packets of the
traffic are discarded when a large number of the packets of the
traffic are long length packets, even if the generated bit error
rate is minimal.
[0010] Yet another problem with packet communication systems is
that even if the traffic discarded data rate that is attributable
to an FCS error of the traffic is measured and the occurrence of
the signal degrade can be detected, after the protection of various
protocols operate, normal traffic other than the control traffic
does not flow in the transmission line. However, control traffic
typically has a higher priority and therefore the control traffic
continues to flow. As a result, most of the normal traffic
disappears, and the discarded data rate of the normal traffic
becomes essentially 0. In this case, the signal degrade of the
transmission line cannot continue to be detected because there is
no normal traffic flowing, and accordingly, a restoration from the
signal degrade is mistakenly caused to be detected, and the
protection is canceled even when the degrade is not really
restored.
[0011] The cancellation of the protection leads to another problem
that once the protection is canceled, the traffic before the
occurrence of the protection flows again in the transmission line,
the signal degrade of the transmission line is erroneously detected
again, and the protection is erroneously generated again, etc.
SUMMARY OF THE INVENTION
[0012] Exemplary embodiments of the present invention addresses the
above disadvantages and other disadvantages not described above.
Also, the present invention is not required to overcome the
disadvantages described above, and an exemplary embodiment of the
present invention may not overcome any of the problems described
above.
[0013] The present invention provides a signal degrade detecting
method, a signal restoration detecting method, devices for those
methods, and a traffic transmission system, which perform the
detection of the signal degrade and restoration on the basis of the
traffic volume to be discarded in the transmission line.
[0014] According to an aspect of the present invention, there is
provided a method of detecting a signal degrade of transmission
data, said method comprising measuring a discarded data rate of
traffic; and comparing said discarded data rate with a threshold
value to detect the signal degrade.
[0015] According to anther aspect of the present invention, there
is provided a method of detecting a restoration from a signal
degrade of transmission data, said method comprising obtaining a
value by multiplying a threshold value, which is used to detect a
signal degrade, by a multiplier; and comparing a discarded data
rate of a control traffic after a signal degrade with said value to
detect a restoration from the signal degrade.
[0016] According to another aspect of the present invention, there
is provided a method of detecting a restoration from a signal
degrade of transmission data, said method comprising measuring a
discarded data rate of control traffic; if a signal degrade is
detected, saving said discarded data rate as a threshold value; and
comparing a discarded data rate of the control traffic measured
after the signal degrade is detected with said threshold value to
detect a restoration from the signal degrade.
[0017] According to another aspect of the present invention, there
is provided a method of detecting a restoration from a signal
degrade of transmission data, said method comprising measuring a
data error rate of traffic; if a signal degrade is detected, saving
said data error rate as a threshold value; and comparing a data
error rate of the traffic measured after the signal degrade is
detected with said threshold value to detect a restoration from the
signal degrade.
[0018] According to another aspect of the present invention, there
is provided a signal degrade detecting device, comprising measuring
means for measuring a discarded data rate of traffic; threshold
value output means for outputting a threshold value; and detecting
means for detecting a signal degrade by comparing said discarded
data rate with said threshold value.
[0019] According to another aspect of the present invention, there
is provided a signal restoration detecting device, comprising
measuring means for measuring a discarded data rate of control
traffic; and detecting means for detecting a restoration from the
signal degrade by comparing said discarded data rate of the control
traffic with a value resulting from multiplying a threshold value
which is used to detect a signal degrade by a multiplier.
[0020] According to another aspect of the present invention, there
is provided a signal restoration detecting device, comprising
measuring means for measuring a discarded data rate of control
traffic; saving means for, if a signal degrade is detected, saving
said discarded data rate as a threshold value; and detecting means
for detecting a restoration from the signal degrade by comparing a
discarded data rate of the control traffic measured after the
signal degrade is detected with said threshold value.
[0021] According to another aspect of the present invention, there
is provided a signal restoration detecting device, comprising
measuring means for measuring data error rate of traffic; saving
means for, if a signal degrade is detected, saving said data error
rate as a threshold value; and detecting means for detecting a
restoration from the signal degrade by comparing a data error rate
of traffic measured after the signal degrade is detected with said
threshold value.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The above and other aspects of the present invention will
become more apparent by describing in detail exemplary embodiments
thereof with reference to the accompanying drawings, in which:
[0023] FIG. 1 is a diagram showing a configuration of a signal
degrade/restoration detecting device according to an exemplary
embodiment of the present invention;
[0024] FIG. 2 is a flowchart showing a detecting process according
to an exemplary embodiment of the present invention using the
signal degrade/restoration detecting device of FIG. 1;
[0025] FIG. 3 is a diagram showing a configuration of a signal
degrade/restoration detecting device according to another exemplary
embodiment of the present invention;
[0026] FIG. 4 is a flowchart showing a detecting process according
to another exemplary embodiment of the present invention using the
signal degrade/restoration detecting device of FIG. 3.
[0027] FIG. 5 is a diagram showing a configuration of a signal
degrade/restoration detecting device according to yet another
exemplary embodiment of the present invention;
[0028] FIG. 6 is a flowchart showing a detecting process according
to another exemplary embodiment of the present invention using the
signal degrade/restoration detecting device of FIG. 5; and
[0029] FIG. 7 is a diagram showing a configuration of a
transmission system according to an exemplary embodiment of the
present invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE PRESENT
INVENTION
[0030] FIG. 1 is a diagram showing a configuration of a signal
degrade/restoration detecting device according to an exemplary
embodiment of the present invention, and FIG. 2 is a flowchart
showing a detecting process using the signal degrade/restoration
detecting device of FIG. 1.
[0031] As shown in FIG. 1, the signal degrade/restoration detecting
device 10 comprises a traffic discarded data rate measuring unit 12
which measures a discarded data rate of traffic due to the FCS
error, a control traffic discarded data rate measuring unit 13
which measures a discarded data rate of control traffic due to the
FCS error, a signal degrade detection threshold value output unit
14, a signal degrade generation detecting unit 15, a discarded data
rate saving unit 16, and a signal degrade restoration detecting
unit 17. One having ordinary skill in the art will appreciate that
the discarded data rate may be a discarded byte rate or a discarded
bit rate. The inputs of the traffic discarded data rate measuring
unit 12 and the control traffic discarded data rate measuring unit
13 are connected to a transmission line 11.
[0032] The traffic discarded data rate measuring unit 12 measures a
discarded data rate A of the traffic due to the FCS error of
traffic (i.e., a normal traffic and a control traffic) that flows
in the transmission line 11.
[0033] The control traffic discarded data rate measuring unit 13
measures a discarded data rate B of the traffic due to the FCS
error of the control traffic that flows in the transmission line
11.
[0034] The signal degrade detection threshold value output unit 14
stores a value, which is a threshold value C for detecting the
occurrence of the signal degrade. The value may be predetermined,
for example, by a host control unit (not shown) such as the
transmitting device.
[0035] The signal degrade occurrence detecting unit 15 compares the
discarded data rate A of the traffic due to the FCS error which is
measured by the traffic discarded data rate measuring unit 12 with
a threshold value C that is given from the signal degrade detection
threshold value output unit 14 to detect an occurrence of the
signal degrade. The signal degrade occurrence detecting unit 15
indicates a signal degrade when the rate A exceeds the threshold
value C.
[0036] Upon detection of a signal degrade by the signal degrade
occurrence detecting unit 15, the discarded data rate saving unit
16 records the discarded data rate B of the traffic due to the FCS
error of the control traffic which is measured by the control
traffic discarded data rate measuring unit 13 as a rate D.
Thereafter, the discarded data rate of the control traffic keeps
changing and continues to be measured by the control traffic
discarded data rate measuring unit 13.
[0037] The signal degrade restoration detecting unit 17 compares
the rate B that is measured by the control traffic discarded data
rate measuring unit 13 with the rate D that is recorded in the
discarded data rate saving unit 16 in order to detect a restoration
from the signal degrade. The restoration from the signal degrade is
detected if the rate B is lower than the rate D.
[0038] Subsequently, the operation of this exemplary embodiment
will be described with reference to FIG. 2.
[0039] Referring to FIGS. 1 and 2, the discarded rate A of the
traffic that flows in the transmitting line 11 is measured by the
traffic discarded data rate measuring unit 12 (hereinafter referred
to as "measuring unit 12).
[0040] The discarded rate B of the control traffic that flows in
the transmitting line 11 is measured by the control traffic
discarded data rate measuring unit 13 (hereinafter referred to as
"measuring unit 13").
[0041] In the signal degrade occurrence detecting unit 15, the rate
A that is measured by the measuring unit 12 is compared with the
threshold value C from the signal degrade detection threshold value
output unit 14 (operation S21) to determine if the rate A exceeds
the threshold value C. If the rate A exceeds the threshold value C
(yes in operation S21), the occurrence of the signal degrade is
detected by the signal degrade occurrence detecting unit 15
(operation S22).
[0042] The rate B that is measured by the measuring unit 13 at the
time of detecting the occurrence of the signal degrade is recorded
in the discarded data rate saving unit 16 as rate D (operation
S23).
[0043] The rate B continues to be measured. Thereafter, the rate B
that is measured by the measuring unit 13 is compared with the rate
D that is recorded in the discarded data rate saving unit 16 by the
signal degrade restoration detecting unit 17 to determine whether
the control traffic discarded data rate B is lower than the
threshold value D (operation S24). If the rate B is lower than the
threshold rate D (yes in operation S24), a restoration from the
signal degrade is detected by the signal degrade restoration
detecting unit 17 (operation S25).
[0044] As described above, according to the configuration of this
exemplary embodiment, since the occurrence of the signal degrade is
detected by using the discarded data rate due to the FCS error of
the traffic that flows in the transmission line, it is possible to
measure the traffic volume that has been actually discarded by the
transmission line. Therefore, the occurrence of the signal degrade,
that is, the occurrence of a state where no traffic flows can be
detected even in a situation where a large amount of traffic is
discarded by the FCS error and where the bit error rate is
slight.
[0045] Moreover, when the signal degrade occurs in the traffic that
flows in the transmission line, and the protection is effected on
the traffic and the normal traffic does not flow, it is possible to
detect the signal degrade and restoration.
[0046] According to the configuration of this exemplary embodiment,
the discarded data rate of the control traffic at the time of
occurrence of the signal degrade is recorded as rate D and used as
the threshold value for the discarded data rate of the control
traffic in order to detect the restoration of the signal degrade.
Thus, it is measured whether the discarded data rate of the traffic
that flows after occurrence of the signal degrade is lower than a
threshold value of the signal degrade detection, or not. As a
result, even if the traffic that flows after occurrence of the
signal degrade changes, the occurrence of the signal degrade can be
continuously detected, and the repetition of the occurrence of the
signal degrade and the detection of the restoration can be
prevented.
[0047] FIG. 3 is a diagram showing a configuration of a signal
degrade/restoration detecting device according to another exemplary
embodiment of the present invention.
[0048] As shown in FIG. 3, a signal degrade/restoration detecting
device 30 comprises a control traffic discarded data rate measuring
unit 33 which measures a discarded data rate of control traffic due
to the FCS error, a signal degrade detection threshold value output
unit 34, a signal degrade generation detecting unit 35, and a
signal degrade restoration detecting unit 37.
[0049] In this exemplary embodiment, the discarded data rate of the
control traffic due to the FCS error is used to detect both of a
degrade and restoration of the signal. Accordingly, as shown in
FIG. 3, in this exemplary embodiment, the output of the control
traffic discarded data rate measuring unit 33 is connected to the
signal degrade occurrence detecting unit 35, and the output of a
signal degrade detection threshold value output unit 34 is
connected to the signal degrade restoration detecting unit 37.
[0050] The operation of this exemplary embodiment will now be
described with reference to FIG. 4.
[0051] The control traffic discarded data rate measuring unit 33
(hereinafter referred to as "measuring unit 33") measures a
discarded data rate B due to the FCS error of the control traffic
which flows in the transmission line 31.
[0052] In the signal degrade occurrence detecting unit 35, the rate
B that is measured by the measuring unit 33 is compared with a
threshold value C from the signal degrade detection threshold value
output unit 34 to determine if the control traffic discarded data
rate B due to FCS error exceeds the threshold value C (operation
S46). If the rate B exceeds the threshold value C (YES in operation
S46), it is determined that a signal degrade has occurred and the
signal degrade is detected (operation S47).
[0053] Thereafter, the control traffic discarded data rate B
continues to be measured by the measuring unit 33. The rate B that
is measured by the measuring unit 33 is then compared with a value
resulting from multiplying the threshold value C by an optional
multiplier by the signal degrade restoration detecting unit 37 in
order to determine if the rate B is lower than the value (operation
S48). If the rate B is lower than the value resulting from
multiplying the threshold value C by the optional multiplier, a
restoration from the signal degrade is detected by the signal
degrade restoration detecting unit 37 in operation S49.
[0054] As described above, the discarded data rate of the control
traffic due to the FCS error is used in the detection of the signal
degrade as well as the restoration, thereby making it possible to
detect the signal degrade of the traffic and the restoration
thereof.
[0055] FIG. 5 is a diagram showing a configuration of a signal
degrade/restoration detecting device according to yet another
exemplary embodiment of the present invention.
[0056] This exemplary embodiment uses a Synchronous Digital
Hierarchy (SDH) based component to measure a bit error rate of the
transmission.
[0057] As shown in FIG. 5, a signal degrade/restoration detecting
unit 50 comprises a traffic discarded data rate measuring unit 52,
a signal degrade detection threshold value output unit 54, a signal
degrade generation detecting unit 55, a bit error rate measuring
unit 53 that measures a bit error rate with the aid of a function
of SDH instead of measuring the discarded data rate due to the FCS
error of the control traffic that flows in the transmission line
51, a bit error rate saving unit 56 that saves the bit error rate
that is measured by the bit error rate measuring unit 53 instead of
saving the control traffic discarded data rate due to the FCS error
at the time of detecting the occurrence of the signal degrade, and
a signal degrade restoration detecting unit 57 that detects the
restoration from the signal degrade by comparing a bit error rate E
that is measured by the bit error rate measuring unit 53 and a bit
error rate F that is saved in the bit error rate saving unit
56.
[0058] The operation of this embodiment will now be described with
reference to FIG. 6.
[0059] The rate A that is measured by the traffic discarded data
rate measuring unit 52 and the signal degrade detection threshold
value C that is output from the signal degrade detection threshold
value output unit 54 are compared with each other by the signal
degrade occurrence detecting unit 55 in order to determine whether
the rate A exceeds the threshold value C (operation S60). If the
rate A exceeds the signal degrade detection threshold value C (YES
in operation S60), a signal degrade is detected (operation
S61).
[0060] The bit error rate F from the bit error rate measuring unit
53 at the time of detecting the signal degrade is saved in the bit
error rate saving unit 56 (operation S62).
[0061] The bit error rate (E) continues to be measured after the
time of detecting the signal degrade (operation S63). Thereafter,
the bit error rate E that is measured by the bit error rate
measuring unit 53 and the bit error rate F that is saved in the bit
error rate saving unit 56 are compared with each other by the
signal degrade restoration detecting unit 57 to determine if the
bit error rate E is lower than the bit error rate F (operation
S64). If the bit error rate E is lower than the bit error rate F
(YES in operation S64), a restoration from the signal degrade of
the normal traffic is detected (operation S65).
[0062] As described above, according to the configuration of this
exemplary embodiment, the signal degrade of the traffic is detected
by using the discarded data rate due to the FCS error of the
traffic while the restoration from the signal degrade of the normal
traffic is detected by using the bit error rate that is measured by
the SDH system at the time of detecting the signal degrade and the
bit error rate which is subsequently measured by the SDH system.
Therefore, it is possible to detect the restoration of the signal
degrade of the normal traffic without measuring the discarded data
rate due to the FCS error of the control traffic as in the first
exemplary embodiment.
[0063] FIG. 7 is a diagram showing a configuration of a traffic
transmission system according to yet another exemplary embodiment
of the present invention.
[0064] A traffic transmission system 70 comprises a plurality of
nodes in a network transmission system (i.e., a traffic
transmission system), as shown in FIG. 7. That is, the traffic
transmission system 70 comprises, for example, a transmitting side
node 80 and a receiving side node 90 which are coupled together by
transmission line 100. This configuration of nodes is only
illustrative, and one having ordinary skill in the art would
recognize that additional nodes are possible.
[0065] The transmitting side node 80 comprises a transmitting unit
81, a receiving unit 82, and a protection control unit 83.
[0066] The receiving side node comprises a receiving unit 91, a
transmitting unit 92, a signal degrade/restoration detecting device
94, and a signal degrade occurrence/extinction notifying unit 93.
Any of the above-described signal degrade/restoration detecting
devices may be used as the signal degrade/restoration detecting
device 94. That is, the signal degrade/restoration detecting device
94 may be the signal degrade/restoration detecting device 10 shown
in FIG. 1, the signal degrade/restoration detecting device 30 shown
in FIG. 3, or the signal degrade/restoration detecting device 50
shown in FIG. 5. The transmitting side node 80 and the receiving
side node 90 are coupled to each other through the transmission
line 100.
[0067] In the above-described system, the signal
degrade/restoration detecting unit and signal degrade
generation/extinction notifying unit are included as part of the
receiving side node 90. However, as an alternative, it is possible
to include a signal degrade/restoration detecting unit and a signal
degrade generation/extinction notifying unit as part of the
transmitting side node 80 instead of the receiving side node 90,
Moreover, it is also possible to include a signal
degrade/restoration detecting unit and a signal degrade
generation/extinction notifying unit in both the transmitting side
node and the receiving side node.
[0068] For convenience in describing the operation of the traffic
transmission system 70, the normal traffic and the control traffic
are transmitted from the transmitting unit 81 of the transmitting
side node 80 through the transmission line 100 to the receiving
unit 51 of the receiving side node 50.
[0069] The receiving unit 91 of the receiving side node 90 receives
the normal traffic and the control traffic which flow in the
transmission line 100, and transfers the traffic to the signal
degrade/restoration detecting device 94. The transfer is performed
by transferring the control traffic and the normal traffic to the
signal degrade/restoration detecting device 94, or by transferring
the control traffic to the signal degrade/restoration detecting
device 94 according to the signal degrade/restoration detecting
device used as the signal degrade/restoration detecting device
94.
[0070] If the signal degrade is detected by the signal
degrade/restoration detecting device 94, signal degrade occurrence
information is transferred to the signal degrade
occurrence/extinction notifying unit 93. The signal degrade
occurrence information that is transferred to the signal degrade
occurrence/extinction notifying unit 93 is inserted into the
control traffic that is transmitted from the transmitting unit 92
to the receiving unit 82 of the transmitting side node 80, and then
the control traffic is transmitted from the transmitting unit 92 to
the receiving unit 82 of the transmitting side node 80.
[0071] When the receiving unit 82 receives the control traffic, the
signal degrade occurrence information in the control traffic is
extracted and transferred to the protection control unit 83. The
protection control unit 83 sets a protection with respect to the
normal traffic that is transmitted from the transmitting unit 81
according to the received signal degrade occurrence
information.
[0072] When a restoration from the signal degrade occurs, the
restoration from the signal degrade is detected by the signal
degrade/restoration detecting device 94, and the detection
information is transferred to the signal degrade
occurrence/extinction notifying unit 93. The signal degrade
occurrence/extinction notifying unit 93 transfers the signal
degrade extinction information to the transmitting unit 92. The
signal degrade extinction information is inserted into the control
traffic that is transmitted from the transmitting unit 92 to the
receiving unit 82 of the transmitting side node 80, and then the
control traffic is transmitted from the transmitting unit 92 to the
receiving unit 82 of the transmitting side node 80.
[0073] When the receiving unit 82 receives the control traffic, the
signal degrade restoration information in the control traffic is
extracted and transferred to the protection control unit 83. The
protection control unit 83 cancels the protection with respect to
the normal traffic that is transmitted from the transmitting unit
81 according to the received signal degrade extinction
information.
[0074] As described above, when the signal degrade is detected by
the discarded data rate at the receiving side, the transmitting
side is notified of the occurrence of the signal degrade, and the
protection is effected on the normal traffic. Because the discarded
data rate or the bit error rate at the time of signal degrade is
saved, and the signal degrade restoration is precisely detected,
the erroneous repetition of the occurrence of the signal degrade
and the signal degrade restoration may be prevented.
[0075] In the above-described exemplary embodiments of the present
invention, the various units may be implemented using one or more
integrated circuits. For example, the measuring units, the output
units, the detecting units and the saving units may be implemented
using an Application Specific Integrated Circuit (ASIC). The
various units may also be implemented as respective dedicated
hardware circuits, or as selectively configurable hardware
circuits, or as software executed by a processor (e.g., a central
processing unit (CPU) or a digital signal processor (DSP)), or as a
combination of any of these. In the case of implementation by
software, it may be appreciated that the flowchart drawings may
represent processing modules and/or information flow through the
processing stages, but without any limitations as to execution
timing.
[0076] In any of the above-described exemplary embodiments, the
result of the detection may be stored in a recording medium.
[0077] While certain exemplary embodiments of the present invention
have been described above, it is to be understood that numerous
modifications to the exemplary embodiments of the invention will be
apparent to those skilled in the art without departing from the
spirit and scope of the present invention.
* * * * *